Conduit under patio


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Old 06-19-14, 08:47 PM
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Conduit under patio

I have a 21 foot deep patio off the back of my house (flush with back of house) that has grass behind it. I've bored under the patio toward the house for a conduit run. Are there any devices or methods I can employ to detect the approximate location of where the nose of the conduit run has landed without breaking up a 2x2 of the slab and digging? Also, can a bilco style access panel be installed on a slab that is about 9 years old? Anything like an access panel in a 2x2 size?.
 
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Old 06-19-14, 10:01 PM
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If there is no steel re-rod in the cement then you can use a basic metal detector to locate a metal conduit.
 
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Old 06-20-14, 09:31 PM
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Do you really mean the concrete is 21' thick (deep)? How many Saturn rockets do you launch from it in a typical year?
 
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Old 06-20-14, 11:10 PM
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I hope it's not 21' deep. ........ I took it as the patio is 21' wide.
 
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Old 06-21-14, 03:46 AM
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at least you're below the anticipated 100,000yr frost depth no matter where you are in ny i'd suspect, if you've bored all 21', you'd have run up against the bsmt wall by now curious how you bored horizontally - that's a fair amount of work

the conc age won't matter if you install it correctly when making the opening tho condition is different factor,,, assuming conc's in good shape, we'd diamond sawcut 2" perimeter cut & chip away w/30# bosch
 
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Old 06-21-14, 03:50 PM
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Apologies all, yes concrete is 4" thick. The patio is about 50x21. I actually had an idea yesterday. My patio and driveway are both flanked on the outer edges by 6x9 stone blocks. If the spot in the slab I cut, is kept to 9", I can use similar stone with mortar to fill, correct?
 
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Old 06-21-14, 04:00 PM
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Stadry, I bored that distance with 1.25" and 1.5" conduit. I had to do it very methodically. First, I trenched alongside my garage walkway about 15'. I kept it all straight and the straight line, lines up dead center between my bilco doors, and my back steps (space between them is 2'). Dug it to a depth of 21". I then took my first section of conduit and drove it in, two to three inches at a time, would pull it back out, dump the dirt and sand, then repeat again and again. It took me 8 hours to go nine feet. Then I added my second section of conduit and bolted them together to continue, however I then cut the lead conduit section into the shape of a chisel. It took only two and a half hours to do the next 11 feet. So I know I have the length in I need, just need to know I'm accurate. I've also considered bolting a chisel to the lead section of concrete to get me through the wall....

Yes, I'm fairly confident I am at or near the wall, as I've finally hit a fair amount of resistance now, unlike any rocks etc.

Don't think this has gone perfect... The first section of conduit which was EMT, wound up bent up, and had to winch it out with my truck. Perseverance has been key. A lot of people have told me I am nuts for even attempting this. I got one quote which was over $1000 for a guy working by himself with a bullet mole. I have spent only about $150 on supplies and materials and I am 90% done now. Just this last breach and that's it.
 
 

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